Pilot tool for centering and clamping

ABSTRACT

A tool for centering and clamping of at least a part (P) to be fixed in position and comprising a through passage and adjusted for the tool, comprises a pilot device borne at the end of a case having an upper face forming a support for the part and clamping members. The tool further comprises elements for driving the clamping members between a centering position in which the clamping members are retracted into the pilot device and a plurality of clamping positions in which the clamping members project outside the pilot device and rest on the part (P). The driving elements are arranged for simultaneously pivoting and translating the clamping members between the centering position and the clamping position. The invention is useful for handling parts to be fixed in position.

CROSS REFERENCE TO RELATED APPLICATION

This is the 35 USC 371 national stage of International applicationPCT/FR97/02411 filed on Dec. 23, 1997, which designated the UnitedStates.

FIELD OF THE INVENTION

The present invention relates to the field of centering and grippingtools for handling pieces to be fixed in position such as metal sheetand, more generally, a centering and gripping tool of at least onemember comprising a guide member carried by the end of a casing,gripping members and drive means for the gripping members between acentered position in which they are retracted within the guide memberand a plurality of gripping positions in which the gripping membersproject outside the guide member and bear on the piece.

BACKGROUND OF THE INVENTION

Known gripping tools generally comprise a hydraulic or pneumatic jackpermitting actuation of a gripping member such as a gripping arm whichis drivable pivotably between an active gripping position on the pieceand an inactive position. Such a tool can also comprise a guide which isintroduced into a passage provided in the piece to be treated, whichpermits correctly centering the tool on the piece.

From FR-A-2 340 798, there is known a gripping tool whose gripping armcomes into abutment against the piece to be gripped by pivotably drivingthis gripping arm. This pivotal driving of the gripping arm between therelease position and the gripping position is obtained by an articulatedlinkage mounted on a rod driven in linear displacement by a jack.

This pivotal movement of the gripping arm in this type of gripping toolhas the drawback that, with certain pieces to be treated, there isobtained bad gripping, for example when the surface of the piece to betreated is not perfectly flat. In this case, the gripping arm is notalways correctly positioned on the piece and does not guarantee goodgripping. There exists moreover the risk of deformation of the piece.

Moreover, in the case of a gripping tool provided with a guide, thecontact point of the gripping arm on the piece is relatively far fromthe centering point of the tool on said piece, which can give rise to acertain unbalance or require a more complicated structure of the tool.

There is known from WO-A-9635547, an indexing device for a piece througha hole in the piece and comprising a sleeve having an upper surfaceforming an abutment for a piece, a piston mounted in the sleeve to slideunder the influence of drive means between a retracted position withinthe sleeve and an extended position in which it projects from the upperabutment surface of the sleeve by an end portion forming an indexingpin, a restraining jaw for the piece on the upper abutment surface ofthe sleeve, movably mounted on the centering pin and means to controlthe jaw comprising a slide mounted in an axial bore of the piston andhaving an end forming a cam. These control means are constituted by aslide mounted in an axial bore of the piston to slide under theinfluence of drive means between a first position in which it ensuresthe locking of the jaw in its active position by means of an activeportion forming a cam driving in pivotal movement the gripping jawstoward said active position, and a second position in which it releasesthe locking of this jaw by controlling the pivoting of the gripping jawstoward the inactive position.

The drive means comprise among other things a first return springdisposed between the piston and the sleeve to return the piston to itsextended position and a second return spring disposed between the sleeveand the slide to return the slide toward its unlocking position of thejaw.

The axial movements of the piston within the sleeve and of the slide inthe piston are controlled by a jack. A principal drawback of this typeof device is that, in the case of accident, for example upon a cutoff ofthe air supply, the jack no longer operates and thus, the second returnspring blocks the device in the gripping position. Accordingly, in thegripping position, it is thus not possible to free the piece thus held.

Moreover, this structure is relatively complicated and the wear,particularly expansion of the springs, can give rise to correctpositioning problems of the jaws with the passage of time.

SUMMARY OF THE INVENTION

So as to overcome these drawbacks, the present invention has for itsobject a centering and gripping tool of at least one piece to be fixedin position and having a through-passage suitable for said tool, of thetype comprising a guide member carried at the end of a casing having anupper surface forming an abutment for said piece, gripping members anddrive means for the gripping members between a centered position inwhich the gripping members are retracted within the guide member and aplurality of gripping positions in which the gripping members project tothe exterior of the guide member and bear on the piece, characterized inthat the drive means are arranged to drive simultaneously pivotably andin translation said gripping members between the centered position and agripping position.

Thus, the gripping members are correctly positioned on the piece to befixed in the course of the step of centering carried out by theemplacement of the guide member through the through-passage which issuitable for the piece and the pivotal drive of the gripping memberspermits the drive to extend said gripping members outside the guidemember and their lowering on opposite sides of the guide member to comeinto bearing against the piece to be fixed in position, the simultaneousdriving in translation of said gripping members leading to the grippingof the piece to be fixed in position against the end of the casing, onthe upper surface of which casing there is formed an abutment. Thus,there is ensured complete deployment of the gripping members projectingfrom the guide member and there is obtained a plurality of grippingpositions on the piece to be secured.

Preferably, a first end of the gripping members coming into contact withthe piece to be secured has abutment means, such as a finger, suitableto come into bearing against the edge of the through-passage andsuitable for the piece to be fixed upon simultaneous action in pivotalmovement and translation, of the gripping members from the centeredposition and toward a gripping position of the pieces to be fixed.

According to another preferred embodiment, the gripping members areconstituted by two levers articulated about a medial axis to form adeformable X, each lever having a first end having abutment means andwhose second opposite end to the abutment means is connected to thedrive means such that, under the influence of said drive means, saidsecond ends of the levers are movable in translation, toward and awayfrom each other, the first ends of said levers being thus drivenpivotably and simultaneously in translation, because of the deformationof the X formed by said levers.

Preferably, the levers are elbowed about their axis of articulation andtheir second end is mounted pivotably about an axle mounted movably intranslation in a guide groove of the casing, the end of the linksarticulated on said second ends of the lever being also mountedpivotably about said axes, such that the driving in translation of theslide gives rise, by means of the links, to a driving in translation ofthe axles in the groove which causes the second ends of the levers tomove toward or away from each other and, as a result, because of thedeformation of the levers, the simultaneous driving and pivotingmovement and in translation of the first ends of the levers.

In the centered position, the gripping members are retracted within theguide member which has a slot for this purpose. This slot places incommunication the interior of the gripping and centering tool with theoutside. In particular, it renders accessible the gripping members andthe drive means. According to a preferred embodiment, the abutment meanshave a play such that, in the gripping position, said abutment meansclose the slot of the guide member thereby protecting the interior ofsaid gripping and centering tool, in particular against spattering ofsolder which could enter into said tool upon working the secured piece.There is thus avoided all risk of clogging of the mechanism of thegripping members and drive means.

There is thus obtained a tool whose centering and gripping on a piece tobe secured are reliable, the gripping members acting on the piece to besecured at the level of the passage through which they are engaged bothto permit gripping of said piece and to permit protection of said toolagainst clogging during welding.

BRIEF DESCRIPTION OF THE DRAWINGS

Other advantages and characteristics of the invention will become moreapparent in the course of the following description of an example of apreferred embodiment of the invention, with reference to the drawings,in which:

FIG. 1 is a side cross-sectional view of a centering and gripping toolaccording to the invention, in the centering position; and

FIG. 2 shows a side cross-sectional view of a tool according to FIG. 1in the gripping position.

DETAILED DESCRIPTION OF THE INVENTION

The centering and gripping tool 1 according to the invention comprises acasing 2 at the end of which is mounted a guide member 3 adapted topermit centering of the tool 1 on a piece P to be secured by passingthrough a suitable through-hole of said piece P. The casing 2 has anupper surface 2′ it forming an abutment for the piece P.

The gripping members 5 comprise at a first end 5′ a gripping finger 5′aand are arranged to be disposed within the guide member 3 in thecentered position of the tool 1 (see FIG. 1).

The casing 2 also contains the drive means for the gripping members 5.

The gripping members are constituted by elbowed levers 5, articulatedabout a medial axle 4 so as to form a deformable X.

The levers 5 are positioned in the casing 2 such that their first end 5′projects outside the casing 2 and, in the centered position of the tool1, is disposed in a slot in the guide member 3 and their second end 5″is disposed in the casing 2.

The second ends 5″ of the levers 5 are pivotally mounted respectivelyabout an axle 6 movably mounted in translation in rectilinear guidegrooves 7 of the casing 2, such that a driving in translation of theaxles 6 in the groove 7 of the casing 2 causes the moving together andthe spacing apart of the second ends 5″ of the levers 5 along a linearpath, and, as a result, because of the deformation of the X formed bythe levers 5, simultaneous driving in pivotal movement and intranslation of the first ends 5′ of the levers 5 which, from thecentered position in which they are retracted within the guide member 3,are driven to project outside said guide member 3 and to lower onopposite sides of said guide member to grip the piece P to be secured.

The translatory drive of the second ends 5″ of the levers 5 is effectedby two links 8 articulated on said second ends 5″ by means of axles 6 ofthe second ends 5″ of each lever 5.

Thus, one end of a first link 8 is connected pivotally to a second end5″ of a first lever 5 by means of a first axle 6 and one end of thesecond link 8 is pivotally connected to the second end 5″ of the secondlever 5 by means of the second axle 6.

Another end of the links 8 is mounted pivotally about an axle 9 at oneend of a slide 11 controlled by a jack 10 such that the driving andtranslation of the piston of the jack 10 gives rise to the translatorydisplacement of the axles 6 in the groove 7, whose longitudinal axis isperpendicular to the longitudinal axis of the slide 11 as is seen in thedrawings, giving rise to the spacing or the moving together in a sameplane of the second ends 5″ of the levers 5.

Thus, in the centered position, as shown in FIG. 1, the links 8 formsubstantially a V such that the articulation axles 6 are brought towardeach other in the groove 7. The second ends 5″ of the levers 5 are alsobrought toward each other such that the X formed by the levers 5 isalmost closed, the first ends 5′ of the levers 5 thus being similarlybrought together so as to be disposed within the drive member 3. Therecan be provided an element 12 which, connected on the one hand to thecasing 2 and on the other hand to a link 8, limits the displacement ofthe links 8 and contributes to the good mechanical strength of theassembly.

Upon actuation of the jack 10, the latter drives with lineardisplacement the slide 11 and causes a deformation of the V formed bythe links 8. In particular, jack 10 drives in translation the ends ofthe links 8 mounted pivotably about the axle 9 such that the other endsof the links 8 pivotally rise on the axles 6, driving these latter intranslation in the groove 7.

The links 8 align with each other along the groove 7 (FIG. 2) therebycausing the spacing of the axles 6 within the groove 7 and, as a result,the spacing of the second ends 5″ of the levers 5.

This spacement being carried out by a driving in translation of thesecond ends 5″ of the levers 5 in a same plane, their first ends 5′ aresimultaneously driven pivotally and in translation so as to come intoabutment and into bearing against the edge of the through-passage,adapted and provided in the piece P to be fixed in position, and to gripsaid piece P fixedly against the end of the casing 2 (see FIG. 2).

In the gripping and centering position thus obtained (FIG. 2), the endsof the links 8 pivotally mounted about the axle 9 on the slide 11 formthree aligned points with their opposite ends along the groove 7.

So as to ensure the holding of the tool in this position, in particularin the absence of a source of energy for actuating the jack in thecentered and gripping position, the ends of the links 8 pivotallymounted about the axle 9 are slightly driven beyond the line of thethree points namely slightly beyond the groove 7. There is thusprevented a rearward return of the tool 1, until a new energy sourceactuates the tool 1 toward the reverse position.

A hydraulic or pneumatic jack 10 can be used or electrical drive means.

The guide member 3 can be of the type that is movable relative to thecasing 2 and retractable. In this case, the emplacement of the guidemember 3 through the passage through the piece P to be fixed, can becarried out by drive means common to the gripping members 5, for exampleby actuation of the jack 10.

The guide member 3 can also be fixedly projecting relative to the casing2, and in this case it is the assembly which is driven in displacementto position the guide member 3 through the passage passing through thepiece P.

So as to be able to use a device according to the invention withvariable diameter, height and/or operations concerning the piece to beheld, certain elements enclosed in the upper portion of the casing 2 areinterchangeable whilst the lower portion of the casing encloses the“motor” portion of the device and remains the same.

What is claimed is:
 1. A centering and gripping tool for at least onepiece to be fixed in position and comprising a through-passage and beingsuitable for said tool, the tool comprising: a guide member carried atthe end of a casing having an upper surface forming an abutment for saidpiece and gripping members; drive means for driving the gripping membersbetween a centered position in which the gripping members are retractedwithin the interior of the guide member and a plurality of grippingpositions in which the gripping members project outside the guide memberand bear on the piece; said drive means being structured and arranged todrive simultaneously pivotally and in translation said gripping membersbetween the centered position and a gripping position; said grippingmembers comprising two levers articulated about a median axis to form adeformable X; each lever having a first end having abutment means and asecond end opposite said abutment means connected to the drive meanssuch that, under the influence of said drive means, said second ends aremovable in translation, by moving together or apart, the first ends ofsaid levers being then driven simultaneously in pivoting and intranslation because of the deformation of the X formed by said levers.2. The tool according to claim 1, wherein a first end of the grippingmembers coming into contact with the piece to be secured has abutmentmeans adapted to come into bearing against the edge of thethrough-passage of the piece to be secured upon simultaneous pivotingand translatory actuation of the gripping members from the centeredposition toward a gripping position of the piece to be secured.
 3. Thetool according to claim 2, wherein the abutment means have a clearancesuch that, in the gripping position, said abutment means close a slot ofthe guide member within which they are disposed in the centeredposition, thereby protecting the interior of said centering and grippingtool.
 4. The tool according to claim 1, wherein the drive means comprisea slide controlled by a jack and two links of which one end isarticulated to one end of the slide, and whose other end is connected toa second end of a lever so as to transform the translatory path of thejack into a path of a spacing apart and bringing together the secondends of the lever.
 5. The tool according to claim 4, wherein the leversare elbowed about their axis of articulation and their second end ismounted pivotably about an axle movably mounted in translation within aguide groove of the casing, the end of the links articulated on saidsecond ends of the levers being also pivotally mounted about said axles,such that the translatory driving of the slide gives rise, by means ofthe links, to a driving in translation of the axles in the groove whichgives rise to the bringing together or spacing apart of the second endsof the levers.
 6. The tool according to claim 4, wherein the jack ishydraulic.
 7. The tool according to claim 4, wherein the jack ispneumatic.
 8. The tool according to claim 1, wherein the guide member isfixed in projection relative to the casing.